The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In order to seal such couplings, it is known to insert a seal, such as an O-ring, between the coupling parts, which O-ring is compressed during the screwing-together of the coupling so that the connection is sealed. A problem with such sealing systems for tube couplings with an O-ring is that the O-ring must be positioned correctly at its desired location in order to achieve a sufficient seal. Furthermore, such O-rings are generally made of a compressible, elastic material, which in some cases is prone to damage caused by a process fluid. Such O-rings are also subject to aging, which, in time, can result in a leak in the coupling.
On the other hand, couplings for tube elements are known, which couplings are provided on an end surface of a coupling flange with grooves, with which protruding tongues engage so that a sealing of the coupling is achieved by means of the form fit. In such tube couplings, the groove and the tongue or the projection must be produced with very tight tolerances in order to achieve a sufficient sealing effect. Furthermore, several such grooves and tongues are generally required in order to avoid an undesired escape of the fluid and a leak in the tube coupling.